Photodetectors include a photodetector element constituted by a single element such as a photodiode, a linear sensor constituted by photodetector elements that are aligned on a line, such as a photodiode array, and an area sensor constituted by photodetector elements that are arranged two-dimensionally, such as a CCD sensor and a CMOS sensor.
With respect to sensor output characteristics relating to quantity of received light, there are not only sensors having linearity such as photodiodes, but also sensors having sensing characteristics that have deviations in linearity depending on areas having a small quantity of received light and those having a great quantity of received light, as in the case of area sensors such as CCD sensors and MOS sensors. Those sensors that lack linearity have been considered to be unsuitable for quantitative measurements.
Therefore, the objective of the present invention is to solve problems with linearity that occur when a sensor that lacks linearity in its output characteristics is used in a detector, and consequently to make such a sensor applicable to corresponding measurements.